The SET LIBRARY command enables access to an existing CMS library
    or list of libraries. Subsequent CMS commands automatically refer
    to the library or libraries identified in the SET LIBRARY command.
    The SET LIBRARY command defines logical names beginning with CMS$
    that allow CMS commands to refer implicitly to the library. You
    should not define logical names beginning with CMS$ because this
    prefix is reserved for CMS.

    The SET LIBRARY command performs some consistency checks on the
    directory to verify that it is a valid CMS library (unless you
    specify the /NOVERIFY qualifier). If the library is not valid, you
    receive an error message.

    The library must have been created with the CREATE LIBRARY
    command. During each session in which you want to use your CMS
    library, you must use the SET LIBRARY command before you access
    a library. The command is not required, however, if you have
    just created a library (see the description of the CREATE LIBRARY
    command) because the CREATE LIBRARY command performs an implicit
    SET LIBRARY.

    You create a search list by specifying multiple libraries on
    the SET LIBRARY command. This enables you to manipulate several
    libraries with one command. You must include commas between the
    directory specifications.